The PC is always going to be the premier platform as far as power and versitility go. Really, It\'s a whole different machine for a whole different purpose than consoles, so I don\'t really think it should be in that list.
As far as consoles go, I\'m pretty sure everyone here can agree that the Xbox is the most capable, both in terms of graphics and extras such as the harddrive. The only really limiting thing about the Xbox is it\'s ethernet only modem. They cut out a huge portion of their potential online market by focusing solely on broadband. It\'s a real shame, but at least for those lucky few who have it they\'ll get some kick ass games that were developed with super speed connections in mind.
PS2 online games will be developed with the lowest common denominator in mind.. ala 56k. Though they will still cater to broadband usage, you won\'t have as many features as the Xbox versions do. The trade off, is that you\'ll have far.. far.. more opponents and fellow gamers to meet online. If optimised right, a game built for 56k online play will show very little lag. Sega\'s done a great job making games where the online experience is as seamless as possible. Though it\'s still there (don\'t plan on keeping pace with BB users), it\'s far less laggy than you would ever expect. I\'m sure Sony and their army of developers can create games which provide just as good a online experience over 56k.
I know this thread was talking about "out of the box" capabilities, but I gotta say I also like the idea of making the PS2\'s Harddrive removable. It\'s basically like have a 40 gig memory card which you can swap in and out or trade with your friends. (Though you\'d probably still need 2 PS2\'s linked together for a transfer unless someone makes a device seperate from the PS2 which can transfer data from 1 HDD to another.)